A4
The WHLAXLE4 axle is a TUBULAR style axle made of 4140 HT STEEL alloy. This axle has a 0.625 inch diameter bearing surface. The axle has 0.898 inch four bolt hole pattern on a 1.27 reference circle. This axle assembly comes with the AN4 axle nut

MATCO mfg axles that are aluminum are black anodized and steel axles are yellow zinc.